Zuiko Auto-Macro Lens 50mm f/3.5

Introduction

The 50mm f/3.5 Macro Zuiko is a member of the first series of OM lenses, which were designed with an emphasis on small size and light weight without compromising performance, and it was the first macro lens for a 35mm camera that incorporated floating elements. The lens was designed for optimum performance at a magnification of ×0.1, and the floating elements minimise the aberrations that would normally be expected at higher and lower magnifications.

The lens can focus from infinity to ½ life size. With the addition of a 25 mm Auto Extension Tube, the focusing range can be altered to cover ½ life size to life size (1:1). The extended focusing range compared with a standard 50mm lens requires a longer focusing helicoid, and in order to accommodate this the front element is recessed, providing a built-in lens hood.

The non-macro Zuiko lenses have 2 focusing scales, one in feet with orange markings and the other in metres with white markings. The 50mm f/3.5 Macro Zuiko does not follow this pattern, and has a magnification scale with yellow markings plus one focusing scale in either feet (orange) or metres (white), and so there are separate versions with metric and Imperial focusing scales.

These lenses occasionally appear on auction Web sites with black lettering around the front element, claiming to be a rare and collectable version. This is not correct. Olympus did not make any of these lenses with black lettering – the original white material has subsequently been removed or blacked out.

Going digital

When the Zuiko Auto-Macro 50mm f/3.5 is mounted (alone or with extension tubes) on a digital body using an OM/EOS or OM/Four Thirds adapters, the adapter changes the automatic diaphragm to manual click stops. When it is mounted on the Auto Bellows attached to a digital body, the only ways to close down the iris diaphragm are to use the cable release socket or the stop down lever on the lens mount of the bellows.

The following tables are based on those in the instruction leaflet, with adjustments for different sensor sizes and for any additional extension needed to allow the release lever on the rear of the bellows to clear an overhanging pentaprism or flash.

Instruction leaflet

Generally in close distance photography a standard focal length lens is used in conjunction with attachment lens or auto bellows. This Macro F3.5 is designed primarily for close focusing to meet the photographer’s most exacting definition demands for close-ups, copying work and macro-photography. Usually in lenses of this type the lens barrel tends to become elongated at the closest focusing distance, but the design of this lens made a very compact configuration possible. Additionally, this is the first time that an automatic correction lens group that compensates for close distance aberrations has been built into a macro lens. Because of this new design, this lens produces resolution comparable to that of a standard or normal lens throughout the focusing range. The lens is multicoated.

Its reproduction ratio is from 1/10 to 1/2 life size without attachments. With Extension Tube 25, it extends the limitation from 1/2 to 1:1 life size. But to get best results, it is recommended to use 1:1 Macro 80mm F4 in conjunction with Auto Bellows.

The 1-5 (microprism-clear field type) offers a brighter image, but the meter built into the OM-1 and OM-2 (on MANUAL) does not give correct light readings. With the OM-2 on AUTO, correct exposures are made on the film, but the meter needle does not give correct light readings.

• Depth of Field Table

F stop

Distance scale — Camera-to subject distance (metre)

*0.23

*0.25

*0.3

*0.4

*0.5

*0.7

*1

2

*3

*∞

3.5

0.23–0.23

0.25–0.25

0.30–0.30

0.40–0.40

0.49–0.51

0.68–0.72

0.96–1.04

1.85–2.17

2.67–3.42

23.21–∞

4

0.23–0.23

0.25–0.25

0.30–0.30

0.40–0.40

0.49–0.51

0.68–0.72

0.96–1.04

1.83–2.20

2.63–3.49

20.32–∞

5.6

0.23–0.23

0.25–0.25

0.30–0.30

0.39–0.41

0.49–0.51

0.67–0.73

0.93–1.06

1.77–2.29

2.51–3.74

14.53–∞

8

0.23–0.23

0.25–0.25

0.30–0.30

0.39–0.41

0.48–0.52

0.66–0.74

0.92–1.09

1.69–2.45

2.34–4.18

10.19–∞

11

0.23–0.23

0.25–0.25

0.29–0.31

0.39–0.41

0.48–0.52

0.65–0.76

0.90–1.13

1.60–2.68

2.17–4.91

7.43–∞

16

0.23–0.23

0.25–0.25

0.29–0.31

0.38–0.42

0.47–0.54

0.63–0.79

0.86–1.20

1.47–3.17

1.93–6.93

5.12–∞

22

0.23–0.23

0.24–0.26

0.29–0.31

0.38–0.43

0.46–0.55

0.61–0.82

0.81–1.31

1.34–4.07

1.70–13.81

3.74–∞

Figures with * are engraved on the distance scale.
Circle of least confusion 1/30mm.

• Depth of Field Table

F stop

Distance scale — Camera–to subject distance (feet)

*9″

*10″

*1

*1.25

*1.5

*2

*3

*4

*6

8

10

*∞

3.5

0.75–0.75

0.83–0.83

0.99–1.01

1.24–1.26

1.48–1.52

1.96–2.04

2.90–3.10

3.82–4.19

5.60–6.47

7.28–8.88

8.89–11.43

75.74–∞

4

0.75–0.75

0.83–0.83

0.99–1.01

1.24–1.26

1.48–1.52

1.96–2.05

2.89–3.12

3.80–4.22

5.54–6.54

7.19–9.02

8.74–11.67

66.35–∞

5.6

0.75–0.75

0.83–0.83

0.99–1.01

1.23–1.27

1.47–1.53

1.94–2.07

2.85–3.17

3.73–4.32

5.38–6.79

6.91–9.51

8.34–12.51

47.53–∞

8

0.75–0.75

0.82–0.84

0.99–1.01

1.22–1.28

1.46–1.55

1.91–2.10

2.79–3.25

3.62–4.47

5.15–7.20

6.53–10.35

7.79–14.03

33.36–∞

11

0.74–0.76

0.82–0.84

0.98–1.02

1.21–1.29

1.44–1.56

1.88–2.13

2.72–3.35

3.50–4.68

4.89–7.78

6.11–11.63

7.19–16.54

24.33–∞

16

0.74–0.76

0.82–0.84

0.97–1.03

1.20–1.31

1.42–1.60

1.84–2.20

2.61–3.54

3.31–5.08

4.52–9.01

5.53–14.70

6.38–23.63

16.79–∞

22

0.74–0.76

0.81–0.85

0.96–1.04

1.18–1.33

1.39–1.64

1.78–2.29

2.49–3.80

3.11–5.67

4.14–11.14

4.96–21.55

5.63–49.01

12.26–∞

Figures with * are engraved on the distance scale.
Circle of least confusion 1/760in.